When transporting temperature controlled items such as fruits and vegetables, it is typically important to their quality and safety to maintain a cold chain from harvest, through the distribution chain to the final customer. This process often includes measuring the temperature of the food items within containers at points along the distribution chain. If for example the measured temperature of a food item lot is above a predefined refrigeration temperature, a distributor may refuse to accept the food item lot.
Fruits and vegetable temperature is usually measured with a metal thermometer probe inserted into the product. This type of temperature measurement has several drawbacks. Conventional thermometers respond too slowly for accurate measurement. Additionally, conventional thermometers measure temperature of one piece of produce that may not represent the temperature of an entire lot. The temperature probe penetrates the food item, often causing physical damage to the sampled item and exposing an interior of the food item to contaminants. The probe may also transmit human or plant pathogens from one item to another. Moreover, conventional temperature measurement methods cannot be used with food items that are sold in packages that must remain sealed or undamaged.